linux-kernel - Re: [PATCH] mm, vmscan: Give up balancing node for high order allocations earlier

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Date:	Tue, 12 Jul 2016 14:32:45 +0800
From:	"Hillf Danton" <hillf.zj@...baba-inc.com>
To:	"'Andrew Morton'" <akpm@...ux-foundation.org>
Cc:	"'Mel Gorman'" <mgorman@...hsingularity.net>,
	"'Johannes Weiner'" <hannes@...xchg.org>,
	"'Vlastimil Babka'" <vbabka@...e.cz>,
	"'linux-kernel'" <linux-kernel@...r.kernel.org>,
	<linux-mm@...ck.org>
Subject: Re: [PATCH] mm, vmscan: Give up balancing node for high order allocations earlier

> > To avoid excessive reclaim, we give up rebalancing for high order
> > allocations right after reclaiming enough pages.
> 
> hm.  What are the observed runtime effects of this change?  Any testing
> results?
> 
This work was based on Mel's work, Sir,
"[PATCH 00/27] Move LRU page reclaim from zones to nodes v7".

In "[PATCH 06/27] mm, vmscan: Make kswapd reclaim in terms of nodes", 
fragmentation detection is introduced to avoid excessive reclaim. We bail 
out of balancing for high-order allocations if the pages reclaimed at the 
__current__ reclaim priority are two times more than required.

In this work we give up reclaiming for high-order allocations if the 
__total__ number of pages reclaimed, from the first priority to the 
current priority, is more than needed, and in net result we reclaim less 
pages.

Given " [PATCH 00/34] Move LRU page reclaim from zones to nodes v9" 
is delivered, I will send this work if necessary, after Mel's work landing 
in the -mm tree.

thanks
Hillf